Mechanical hammer



Dec. 14; 1937. B w SNODGRASS 2,101,878

MECHANICAL HAMMER Filed March 24, 1936 4 Sheets-Sheet 1 Benjamin W Snodgrass Dec. 14, 1937. 5. w SNQDGRASS 2,101,878

MECHAN ICAL HAMMER Ben/0min l/l/ ShoQgross Dec. 14, 1937. B, SNQDGRASS 2,101,878

MECHANICAL HAMMEIR' Filed March 24, 1936 4 Sheets-Sheet 3 F/G. l6

INVENTOR Ben 'dmm .GnOQ gr 8 ATTORNEY Dec. 14, 1937. B. w. SNODGRASS' MECHANICAL HAMMER 4 Sheets-Sheet 4 File March- 24, 1936 Ben 0mm W Sven grass- Patented Dec. 14, 1937 UNITED STATES PATENT OFFICE 15 Claims.

This invention relates to mechanicalhammers of self-contained type wherein a prime mover is operatively associated with and for actuation of a ram element in a single, portable unit, and has as an object to provide an impoved construction and arrangement of elements constituting such a. unit.

A further object of the invention is to provide an improved self-contained mechanical hammer unit of enhanced operative efiiciency.

A further object of the invention is to provide improved means operatively interconnecting a prime mover and a reciprocable ram in a mechanical hammer unit.

A further object of the invention is to provide improved speed-controlled means automatically operable to interconnect a reciprocable ram and a prime mover for uniform actuation of said ram.

A further object of the invention is to provide improved means automatically operable to actuate a reciprocable ram in a mechanical hammer in a definite, timed cycle.

A further object of the invention is toprovide improved means automatically operable to interconnect a reciprocable ram and a prime mover in a mechanical hammer for actuation of said ram in a definite, timed cycle.

A further object ofthe invention is to provide an improved mechanical hammer unit comprising a ram freely reciprocable between elastic abutments, a prime mover, and speed-controlled means automatically operable to connect said ram and prime mover for actuation of the latter in a definite, timed cycle.

A further'object of the invention is to provide animproved mounting for a reciprocable ram in a mechanical hammer.

A further object of the invention is to provide an improved operative connection between a reciprocable ram and a rotary driving element in a mechanical hammer.

A further object of the invention is to provide improved speed-controlled clutch means operatively between a reciprocable ram and a prime mover in a. mechanical hammer and automatically operable to limit actuation of said ram to a definite, timed cycle.

A further object of the invention is to provide an improved mechanical hammer unit of simple, relatively inexpensive construction, susceptible of embodiment in a single, compact unit, adapted for practical use in a wide variety of specific fields, and arranged for operative actuation with enhanced eificiency.

My invention consists in the construction, ar-

rangement and combination of elements hereinafter set forth, pointed out in my claims, and

illustrated by the accompanying drawings, in which Figure 1 is a side elevation of a hammer construction embodying the principles of my invention as assembled and arranged for practical use. Figure 2 is a section axially of the construction shown in Figure 1, certain elements being broken away to conserve space. Figure 3 is a cross section, on an enlarged scale, taken on the indicated line 3-3 of Figure 2. Figure 4 is a cross section similar to Figure 3, taken on the indicated line 4-9 of Figure 2. Figure 5 is a cross section similar to Figures 3,and 4, taken on the indicated line 55 of Figure 2. Figure 6 is a section axially of a hammer construction modified somewhat relative to the showing of Figure 2. Figure '7 is a cross section, on an enlarged scale, taken on the indicated line 'l| of Figure 6. Figure 8 is a cross section taken on the indicated line 8-8 of Figure 6. Figure 9 is a fragmentary, detail section axially of an elastic abutment and related element employed in the improved constructicn. Figure 10 is a fragmentary, detail section, on an enlarged scale, axially through the connection between a, ram element and its actuating element. Figure 11 is a fragmentary, detail section similar to Figure 10 and illustrating a somewhat modified construction and relation of the elements shown in Figure 10. Figure 12 is a section axially of a yet further modified practical embodiment of theimproved hammer. Figure 13 is a cross section, onan enlarged scale, taken on the indicated line l3-l3 of Figure 12; Figure 14 is a cross section similar to Figure 13, taken on the indicated line 14-44 of Figure 12. Figure 15 is a fragmentary, detail section, on an enlarged scale, axially through certain actuating elements and connections employed in the improved hammer. Figure 16 is a fragmentary, detail section, on an enlarged scale, axially of ,a relatively rotatable connection employed in the improved hammer. Figure 1'7 is an elevation of an automatic, speed-controlled clutch assembly employed in the improved hammer unit 1 and showing said clutch in its disengaged relaciprocation relative to said housing member.

shown in. Figures 12. and 13, the ram mounting comprises enlarged annular bosses 3 adjacent.

connected, as by means of bolts engaging through annular flanges on adjacent ends of said sections,

in axial alignment to form a rigid assembly. The outer end of thesection 22' is suitably arranged to engage with and be removably secured to the housing 23 of an electric motor, or equivalent prime mover, whereby the driving shaft 24 of the prime mover is disposed at one end of and in axial alignment with the tubular housing assembly. While the tool assembly is shown throughout in operative association with an electric motor, it is to be understood that other equivalent and suitable sources of power may be substituted for the electric motor shown without in any way departing from the principles and spirit of the invention.

, The tubular housing section 2| is relatively long and defines a straight cylindrical chamber wherein a ram element 25, of suitable mass, is mounted for actuation longitudinally of the assembly. Various specific mountings for the ram 25 are illustrated in the drawings. As" shown in Figures 2 and 3, the ram 25 is formed as a cylindrical element of a size to fit loosely within its chamber in the housing 2| and is provided with a plurality of longitudinal ribs 26 extending substantially the' length of the ram and projecting in uniformly-spaced relation radially from the outer surface of said ram, said ribs being grooved longitudinally of their outer faces for engagement with balls 21, or equivalent anti-friction devices, carried by retainer elements 28 adjust-.

ably engaging radially through the housing member 2|. The retainer elements 28 are preferably grouped in two longitudinally spaced assemblies cireumferentially of the member 2|, and thereby provide mountings adjacent the opposite ends of the ram 25 wherein said ram may reciprocate freely and be retained against rotary motion relative to the member 2|. As shown in Figures 6 and 8, the ram 25 provided with the ribs 26 is mounted by means of the balls 21 and retainer elements 28 for axial reciprocation longitudinally of and within a tubular sleeve 29, which latter is mounted for rotation'within and fixed against travel longitudinally of the housing member 2| by means of anti-friction ball bearingassemblies 30 engaging between end; portions of the sleeve 29 and annular races disposed in spaced relation within the housing member 2|, thus mounting the ram 25 for both rotation and axial rethe ends of the ram 25 wherein relatively wide and deep ways 32 are formed in alignment longitudinally of the ram, anti-friction ball bearing assemblies 33 rotatably supported in axially radial relation within the housing member 2| being positioned to engage within the ways 32 at each end of the ram 25 to rollingly support the latter for reciprocation axially of said housing member. While the construction according to Figures 12 and 13 provides for non-rotatable reciprocation of the ram 25, it is to be understood that. the

roller bearing assemblies 33 could conveniently be carried in fixed relation with a sleeve 29 which 'is in turn mounted for rotation within the housopposite ends of the member 2|, the abutment adjacent the power end of the assembly being. illustrated in the form of an expansive coil spring 34 carried by a suitable cup-like retainer 35 disposedwithin the member 2| to bear against anend flange, of said member and thereby position and spring assembly comprising the other of theelastic abutments. As shown, a frusto-conical spring element 36 is seated with its base engaging against the inner end of the annular recess in the housing member and is thereby positioned in axial alignment with the ram 25, the smaller end of the conical spring 36 bearing against a piston-like impact head 31 slidably sealed within a bearing sleeve 38 fitted said annular recess and provided with a retaining rib 39 engaging that face 'of the impact head adjacent the ram to limit travel of said head in one direction, the said impact head being thus axially aligned with the ram and-positioned for engagement at times by the adjacent end of said ram. On the spring side of the impact head 31 the housing 20 is formed with an axial bore opening outwardly-through the end of the housing assembly from the annular recess containing the impact head, which bore is adapted to slidingly receive and support the shank 40 of a tool element operatively associated with the hammer assembly, the inner end of said shank 40 extending within said bore and through the conical spring 36 to engagement with -the adjacent face of the head 31,

cent the spring 34 and projecting through the adjacent end of the housing member 2| into the housing member 22. The specific connection between the stem 4| and ram 25 will vary according to the specific mounting of the ram within its housing member 2 since the stem 4| is arranged to be rotatably as well as axially actuated. When the ram 25 is mounted for rotation as well as axial reciprocation, the stem 4| may be fixedly engaged with said ram through the agency of a connection such as is illustrated in Fig. 10; however, when the ram is non-rotatably mounted, the connection between said ram and the stem 4|must be such as will permit of relative rotation therebetween, a swivel joint effective to permit of such relative rotation being illustrated in Figure 11 as comprising an annular rib'42 projecting in fixed relation inwardly of one'end of the ram 25 for operative engagement with complementary hearing plates 43'- removably carried by the corresponding end of the stem 4|. An annular cam track 44 is fixed to the end of the housing member 2| within the adjacent member 22 in concentric relation with the stem 4| and is disposed with the peaks of its cam lobes directed toward the power end of the assembly, and said stem 4| is provided with a cam follower 45 rotatably mounted in anti-friction bearings carried bysaid stem and disposed in axially-perpendicular, fixed relation with said stem to engage against and traverse the cam track 44. With the foregoing arrangement, rotation of the stem 4| acts to move the follower 45 about the cam track 44 to effect axial displaoement of the stem 4| and ram 25 in accordance with the number and shape of the cam lobes carried by said track, said lobes being so arranged as to permit full driving engagement of the ram against the impact head 31 and tool shank 40 at one extreme and to accelerate the ram 25 to engagement with the spring 34 at the other extreme, the cam lobes consequently having a relatively moderate approach inclination to their peaks in the direction of rotation and dropping off rapidly to the point of greatest cam depth after the cam peak has been passed. To effect power rotation of the stem 4|, a power transmission shaft 46 is journaled for rotation in the housing member 22 in axial alignment with said stem 3! and driving connection between said shaft 46 and stem M is had through complementary, telescoping coupling elements 47 and flflfixed respectively to the shaft 45 and stem ill and operatively interconnected by means of anti-friction balls 59 adjustably supported by retainers 50 mounted radially through the coupling element 41 for engagement within grooves 5i disposed longitudinally of the coupling element 58, thereby providing a rotatably-engaged, axially-variable positive drive between the shaft 56, and stem M.

In the construction shown in Figures 12 to 16,

inclusive, the driving connection between the shaft 15 and stem (ll, is in all functional respects identical with but differs structurally from that above described. As shown in the figures last noted, the shaft 36 fixedly carries a coupling element ll which supports individually-rotatable anti-friction bearing assemblies 52 axially fixed in uniformly-spaced relation radialy of said element, which bearing assemblies are adapted to operatively engage in longitudinal ways 53 formed in the periphery of the complementary coupling element 38' carried by the stem M in telescoping relation with the coupling element 47. The coupling element 48 is preferably mounted for rotation on and fixed against displacement axially of the end of the stem it by means of suitable antifriction bearing assemblies 55, as shown in Figure l6, and is provided with an integral axial hub 55 spaced from and surrounding the stem 4i and directed toward the adjacent end of the housing member 2i. The free end of the hub 54 is pro vided with suitably spaced and contoured cam lobes directed toward the ram 25, which lobes are .adapted to engage against and ride on fixed, ro-

tatable cam followers 56 supported by and projecting radially within a flanged sleeve 5'! fixed mechanically limited in such reciprocation solely by the cam track and follower arrangement em ployed, it is obvious that for efficient actuation of the ram the cam track and follower arrangement should be so designed with reference to the operative speed imparted thereto as to engage for acceleration of the latterfrom the impact head 31 and to release said ram for opposite travel deriving from the spring 34 in" time to free said ram from any mechanical restraint imposed by cam track and follower engagement during such spring-impelled travel. As a consequence, it follows that for every specific combination of given ram actuable between given abutments under the influence of a given speed of drive there is but one cam track and follower arrangement which will function to produce the desired smooth, uniform acceleration and operation of the ram resulting from the application of power impulses accurately synchronized with the recoil velocities resulting from reaction between said ram and said abutments, and, conversely, that for a given cam track andfollower arrangement in operative combination with agiven arrangement of ram and elastic abutments there is butone operative speed for the cam track and follower arrangement which will be productive of smooth, uniform, synchronized I ram actuation between and for reaction from the said abutments. While the shaft 46 could be directly connected to the driving element of the prime mover in constant driving relation with the ram 25 irrespective of the operative speeds of said prime mover, such actuation of the ram would be smooth and efficient only at one driven speed and would be productive of excessive vibration in the assembly, inefiicient power delivery by the ram, and rapidly destructive loads on operating elements of the assembly at speeds of the prime mover other than the one for which such elements have been designed, such inei-licient operation being particularly and inevitably present during the speed variation consequent upon starting and stopping of the prime mover. To insure actuation of the ram with only that prime mover speed for which a cam assembly has been designed, and to provide means adjustable to preserve operative synchronization between ram actuation and prime mover speeds, operative connection between the driven shaft of the prime mover and the shaft 46 is had through an automatically speed-controlled clutch unit illustrated in one specific embodiment in Figures 6, 1'7, and 18.

In the construction shown, which is but a typical embodiment of functionally equivalent arrangements, the shaft 24 is shown in fixed, driving relation with a concentric plate 58 positioned within one end of the housing member 22 in adjacent registration with the open end of a cylindrical, hollow drum 59 carried infixed, concentric relation on the adjacent end of the shaft 56. The plate 58 is free to rotate with the driven shaft of the prime mover independently of the drum 59 and carries a substantially circular, expansive clutch band fill pivotally fixed at one end, as at 6 l,

adjacent a margin of the plate to register with the periphery of said plate and project perpendicularly from the surface of said plat-e in closely spaced, concentric relation with the inner. cylindrical surface of and within the drum 59, so that expansion of the clutch band 60 serves to engage 3* the outer surface of said band with the inner surface of said drum for clutched, simultaneous ro-' tation of said elements. For automatic, speedcontrolled actuation of the clutch band 60, a weighted lever 62 is pivotally engaged at one end,

Iii)

as indicated at 63, with the free end of the clutch band and is pivotally mounted on the plate 58 by means of a pin or support 64 engaging through said lever 62 with said plate eccentrically of the latter andin spaced, adjacent relationwith the pivotal connection 63, thus disposing the weighted, major portion of the lever 62 eccentrically across the plate 58 and in position to swing'outwardly of said plate about its pivotal mounting 64 under the influence of centrifugal force to separate the free and fixed ends of the clutch band 60 and expand said band into clutched engagement with the drum 59. tion of the lever 62 at relatively low speeds, a lug To limit and, restrain actualation with the free end of said lever 62, and a retractile coil spring 66 engages between said lug 65 and lever 62 to normally urge the latter inwardly of'the plate58 and to maintain the clutch band 60 in its contracted position. Since it is desired to expand the clutch band, 66 into engagement with the drum 59 at a certain, definite rotational speed only, the lever 62 is normally.

latched against outward movement relative to the plate 58 by means of a hooked spring arm 61 fixed at one end to the lug 65 and extendin therefrom to engagement of its free hooked end within a notch 68 formed adjacent the free end of the lever 62, said hook and notch being related for automatic interengagement when the lever 62 is moved inwardly of the plate- 58 under the influence of the/spring 66. lease the spring 61 from its hooked engagement with the notch 68 at a definitejrotary speed of the assembly are provided in the form of a weighted arm 69 pivotally engaged at one end with a pin or support "disposed eccentrically across said plate on the opposite side ofthe plate center from the lever 62, the free end of. the arm 69 being arranged to engage against the; free end of the lever 62, when saidelements are in their innermost positions relative to the plate 58. The

arm 69 is adjustably and yieldably held in normal engagement of its free end with the end of the lever 82 by means of an expansive coil spring 1| engag g between said arm and a stud 12 fixedly carried by the plate 58, a threaded arm 13 projecting radially from said stud- 12 engaging within the spring 1| and supporting an adjusting nut 14 in bearing engagement against the end of said spring for adjustable variation in the presand to move outwardly against and flex the spring 61 for release of its hooked engagement with the notch 68 when the arm 68 is moved about its pivot and against the pressure of its spring 1| under the influence of centrifugal action deriving from rotation ofthe plate 58. With the foreand uniform speed. With the clutch assembly outward motion of the'arm 69 with a predeter mined angular velocity of the plate 58, which motion of the arm 69 acts to release the spring'61 from its latched engagement with the lever 62 for outward, centrifugally-infiuenced travel of the latter and consequent clutched engagement of the band 60 with the drum 59, any decrease in the centrifugal force permitting theinherent tension in the c'lutch band 60 and the influence of the spring 66 to return the lever 62 inwardly of the plate 58 for renewal of the latched, inoperative relation ofthe clutch assembly elenients as shown inFigurel'L The clutch arrangement just described constitutes speed-controlled means automatically operable to engage and actuate the ram 25 and associated mechanism when the prime mover has attained a given rotational speed; the clutch assembly being so adjusted as to engage at that driving speed of the prime mover forwhich the ram and cam and follower arrangement has been designed, the prime mover being so constructed or governed as to operate under load at a constant operatively engaging between the prime mover Means operable to re-' and the shaft 46, rain actuation is had only at that driving speed for which the mechanism has been timed, and the ram is inoperative during starting and stopping phases of the prime mover operation and during decrease of prime mover driving speed deriving from variations in power or load factors, thus insuring smooth and highly efficient operation of the tool assembly and eliminating the danger of excess wear and damage repact head 31 is sufficient to rotate said impact head and the tool engaged thereby to the extent desirable in the operation, but when the ram 25 is'held against rotation, it may be desirable to include in the hammer assembly some such mechanical arrangement as is shown in Figures 1 and 2 to automatically and positively rotate the tool. As shown in the figures last noted, the housing member 20 is formed to receive and rotatably support a sleeve 16 disposed in axial alignment with the tool shank 40 and arranged to slidingly receive said tool shank to engage ribs or fins 11 projecting radially in fixed relation from said shank for rotational driving engagement between said sleeve and the tool element. A gear 18 is fixed in concentric relation with the sleeve 16 and meshes through an opening in the housing member 20 with a gear 19 frictionally associated in driven relation with a shaft 60 disposed in axial parallelism with the ram 25 and shaft 46 and journaled for rotation in suitable bearings carried by the housing members 20, 2|, and 22. The shaft #6 is provided with a crank element 8| arranged to cooperate with and actuate ratchet detents 82 projecting through the housing member 22 for operative engagement with a ratchet against rotation through the frictional driven mounting of the gear 19 on the shaft 80. shown in Figures 1 and 2, the end of the housing member 20 may be closed by means of a removable cap 84 through which the tool element is freely slidable, and a suitable hook member 85 may be hinged to said cap to hold the tool element against escape from the hammer assembly, as is common practice. In certain drilling operations it, is desirable to jet water through the drillltool and outwardly of the working face of such tool, to which end the improved hammer assembly may readily be adapted by the mounting of a suitable pump assembly 86 in driven relation with the prime mover for connection of its intake 81 with a suitable source of water supply and for operative connection of its outlet through a suitable conduit 88 engaging through the housing member 20 with an annular groove exteriorly of the impact head 31 and in sealed relation with the sleeve 38, a radial passage 89 in the impact head 31 communicating between said annular groove and an axial passage 90 formed in said head in registering alignmentwith the longitudinal bore 9| of the tool element to provide a continuous passage for liquid delivered by the pump 88 through the tool element and to the working rotatable to actuate said ram, a power unit, and

face of the latter.

Since many changes in the specific form, con- 1 struction and arrangement of the elements shown and described may be had without departing from the spirit of my invention, I wish to be understood as being limited solely by the scope of the append ed claims rather than by any details of the illustrative showing and foregoing description.

I claim as my invention- 1. A mechanical hammer comprising a reciprocable ram, a power unit, and speed-controlled for actuation through a synchronous cycle, a power unit in actuating relation'with said ram, and means automatically operable to limit operative connection between said ram and power unit to driving speed of the latter synchronized with the operative cycle of said ram.

4. A mechanical hammer comprising a ram re- ,eiprocable between spaced abutments, cam means operable to actuate said ram through a synchronous cycle, a power unit in actuating relation with said cam'means, and means engaging between said power unit and cam means automatically operable to limit engagement therebetween to speeds of said power unit synchronized with the operative cycle of said ram.

5. In a mechanical hammer, a reciprocable' ram, a power unit arranged to actuate said ram, and automatic, speed-controlled clutch means engaging between said power unit and ram.

6. In a mechanical hammer, a ram timed for reciprocation through a synchronous cycle between spaced abutments, a power unit, means operatively connecting said power unit and ram, and means automatically operable to limit the operative connection between said power unit and ram to speeds of the former synchronized with the operative cycleot the latter.

'7. In a mechanical hammer, a ram element mounted for free reciprocation through a synchronous cycle between spaced abutments, a power unit, means operable to periodically transmit power acceleration from said unit to said ram, and speed-controlled means automatically operable to limit operative connection between said power unit and actuating means to speeds of said unit synchronized with the operative cycle of said ram.

8. In a mechanical hammer having a reciprocable ram and a power unit arranged to actuate said ram, means-operatively interconnecting said ram and power unit and automatically operable to limit operative connection therebetween $111; predetermined speed range of said power 9. In a mechanical hammer, a reciprocable ram, cam track and follower means relatively automatic, speed-responsive clutch means adapted to operatively engage said power unit and ram actuating means at predetermined speeds oi the former.

10. In a mechanical hammer, a ram mounted for rotation and axial reciprocation, a relatively fixed cam track, a cam follower carried by said ram and arranged to traverse said track during 1 rotation and for reciprocation of said ram, a

power unit adapted to rotate said ram, and automatic, speed-responsive means engaging said power unit and ram for operative interconnection thereof at predetermined speeds of said power unit.

11. In a mechanical hammer, a reciprocable ram, a cam track rotatably carried in fixed axial relation by said ram, relatively fixed cam follower means engageable by said cam track for reciprocation of said ram, a power unit in driving relation with said cam track, and automatic, speed-responsive means intermediate said power unit and cam track adapted to limit operative.

engagement. therebetween to predetermined speeds of said power unit.

12. In a mechanical hammer, a reciprocable ,ram, a power unit, cam and follower means engageable by said power unit to actuate said ram, and normally-disengaged, speed-responsive clutch means intermediate said power unit and ram actuating means arranged to efiect engagement therebetween at predetermined speeds of the former.

13. In a mechanical hammer having a reciprocable ram and means rotatable to actuate said ram, a power unit operatively engageable with said ram actuating means and a normally-disengaged, speed-responsive clutch operatively associated with said power unit and adapted to automatically engage said ram actuating means at predetermined speeds of said unit.

14. In a mechanical hammer having a reciprocable ram, means rotatable to actuate said ram and a power unit engageable with said ram actuating means, 'a clutch drum operatively. associated with said ram actuating means, a clutch band in driven relation with said power unit spaced concentrically within said drum, and speed-responsive means operable to expand said band into clutched engagement with said drum at predetermined speeds of said power unit.

15. In a mechanical hammer having a reciprccable ram, means rotatable to actuate said ram and, a power unit engageable with said ram actuating means, a clutch drum operatively associated with said ram actuating means, an. expansive clutch band in driven relation with said power unit concentrically within said clutch drum, speed-responsive means operable to expand said band into clutched engagement with said drum, and supplementary speed-responsive means normally latching said band-expanding means and automatically releasable at predetermined speeds of the power unit to permit clutched engagement between said band and drum.

- BENJAMIN w. SNODGRASS. 

